Niemann-Pick disease

Definition

Niemann-Pick disease is a group of diseases passed down through families (inherited) in which fatty substances called lipids collect in the cells of the spleen, liver, and brain.

There are four most commonly recognized forms of the disease: Types A, B, C, and D.

Types A and B are also called Type I.

Types C and D are also known as Type II.

Each type involves different organs. It may or may not involve your nervous system and breathing. Each one can cause different symptoms and may occur at different times throughout life.

Alternative Names

Sphingomyelinase deficiency

Causes, incidence, and risk factors

Niemann-Pick disease types A and B occur when cells in the body do not have an enzyme called acid sphingomyelinase (ASM). This substance helps break down (metabolize) a fatty substance called sphingomyelin, which is found in every cell in the body.

If ASM is missing or does not work properly, sphingomyelin builds up inside cells. This kills your cells and makes it hard for organs to work properly.

Type A occurs in all races and ethnicities. It is more common in the Ashkenazi (Eastern European) Jew population.

Type C occurs when the body cannot properly break down cholesterol and other fats (lipids). This leads to too much cholesterol in the liver and spleen and too much of other lipids in the brain. Type C is most common among Puerto Ricans of Spanish descent.

Type D involves a defect that interferes with how cholesterole moves between brain cells. It is a variant of type C. This type has only been seen in French Canadian people in Yarmouth County, Nova Scotia.

Symptoms

Symptoms vary. Other health conditions may cause similar symptoms. The early stages of the disease may only cause a few symptoms. You may never have all symptoms.

Type A usually begins in the first few months of life. Symptoms may include:

Abdominal (belly area) swelling within 3 - 6 months

Cherry red spot in the eye

Feeding difficulties

Loss of early motor skills (gets worse over time)

Type B symptoms are usually milder. They occur in late childhood or the teenage years. Abdominal swelling may occur in young children. There is almost no brain and nervous system involvement, such as loss of motor skills. Some patients may have repeated respiratory infections.

Type C usually affects school-aged children. However, it may occur any time between early infancy to adulthood. Symptoms may include:

Trouble moving the eyes up and down (vertical supranuclear gaze palsy)

Unsteady gait, clumsiness, walking problems (ataxia)

Symptoms of Type D are similar to Type C.

Signs and tests

A blood or bone marrow test can be done to diagnose types A and B. The test can tell who has the disease, but does not show if you are a carrier. DNA tests can be done to diagnose carriers of types A and B.

A skin biopsy is usually done to diagnose types C and D. The health care provider watches how the skin cells grow, move, and store cholesterol. DNA tests may also be done to look for the two genes that cause this type

Treatment

Bone marrow transplants have been done on a few patients with type B with encouraging results. Researchers continue to study possible treatments, including enzyme replacement and gene therapy.

There is no specific treatment for Type D. A new medicine called miglustat is available for the nervous system symptoms of type C.

A healthy, low-cholesterol diet is recommended. However, research does not show that these methods stop the disease from getting worse or change how cells break down cholesterol. However, medicines are available to control or relieve many symptoms, such as cataplexy and seizures.

Support Groups

For more information, visit the National Niemann-Pick Disease Foundation website: www.nnpdf.org

Expectations (prognosis)

Type A Niemann-Pick is a severe disease. It usually leads to death by age 2 or 3.

Those with type B may live into late childhood or adulthood.

A child who shows signs of type C before age 1 may not live to school age. Those who show show symptoms after entering school may live into their mid-to-late teens. Some may live into their 20s.